Unhealthy Abdominal Fat is Increased by Insufficient Sleep

According to new research from the Mayo Clinic, having free access to food and not getting enough sleep both increase calorie intake and, as a result, fat accumulation, particularly unhealthy belly fat.

Lack of sleep was associated with an increase of 9% in total abdominal fat area and an increase of 11% in abdominal visceral fat compared to control sleep, according to the results of a randomized controlled crossover study conducted at Mayo Clinic and conducted under the direction of cardiovascular medicine researcher Naima Covassin, Ph.D. Visceral fat, which accumulates deep within the abdomen around internal organs, is strongly associated with metabolic and cardiac conditions.

The National Heart, Lung, and Blood Institute provided funding for the study, which is published in the Journal of the American College of Cardiology.

Sleep deprivation is frequently a choice of behavior, and this choice is becoming increasingly common. Over one third of adults in the United States do not get enough sleep on a regular basis. This is partly because they work shifts and use smart devices and social networks when they should be sleeping. Also, people tend to eat more when they are awake for longer periods of time without getting more exercise.

“Our findings show that shortened sleep, even in young, healthy and relatively lean subjects, is associated with an increase in calorie intake, a very small increase in weight, and a significant increase in fat accumulation inside the belly,” says Virend Somers, M.D., Ph.D., the Alice Sheets Marriott Professor of Cardiovascular Medicine, and principal investigator of the study.

“Normally, fat is preferentially deposited subcutaneously or under the skin. However, the inadequate sleep appears to redirect fat to the more dangerous visceral compartment. Importantly, although during recovery sleep there was a decrease in calorie intake and weight, visceral fat continued to increase. This suggests that inadequate sleep is a previously unrecognized trigger for visceral fat deposition, and that catch-up sleep, at least in the short term, does not reverse the visceral fat accumulation. In the long term, these findings implicate inadequate sleep as a contributor to the epidemics of obesity, cardiovascular and metabolic diseases,” says Dr. Somers.

Twelve healthy people who were not obese made up the study cohort, and each of them attended two inpatient sessions over the course of 21 days. After a washout period of three months, participants were randomly assigned to either the control (normal sleep) group or the restricted sleep group during one session and the opposite during the subsequent session. Throughout the course of the study, each group had free choice over their meals. Energy intake was monitored and measured by researchers; energy use; body mass; structure of the body; distribution of fat, including visceral or abdominal fat; and biomarkers of appetite that are in use.

The first four days served as a period of acclimatization. All participants were permitted to sleep for nine hours during this time. For the accompanying fourteen days, the restricted sleep group was permitted four hours of sleep and the control group kept up with nine hours. After that came three days and nights of recovery, during which both groups spent nine hours in bed.

When compared to the acclimation stage, the participants consumed approximately 13% more protein and 17% more fat during the sleep restriction phase, which resulted in an increase of over 300 calories per day. The first few days of sleep deprivation saw the greatest increase in consumption, but the recovery period saw consumption return to pre-deprivation levels. Energy use remained generally something very similar all through.

“The visceral fat accumulation was only detected by CT scan and would otherwise have been missed, especially since the increase in weight was quite modest — only about a pound,” Dr. Covassin says. “Measures of weight alone would be falsely reassuring in terms of the health consequences of inadequate sleep. Also concerning are the potential effects of repeated periods of inadequate sleep in terms of progressive and cumulative increases in visceral fat over several years.”

According to Dr. Somers, shift workers and other individuals who are unable to easily avoid disrupting their sleep should be considered for behavioral interventions, such as increased exercise and healthy food choices. The relationship between these findings in healthy young people and those at higher risk, such as those who are already obese, have metabolic syndrome, diabetes, or both, requires additional research.